**1.1.2.1 Research status of biodegradable film materials**

Biodegradable materials research began in the 1960s. The initial study was mainly to add natural polymers with biodegradable properties (such as starch, etc.) to generic plastic, then get the so-called biodegradable materials. St.Lawrence starch-company developed a starch– polyethylene or polypropylene blends in Canada (Qiu Weiyang, 2002). With human understanding of biodegradability of macromolecule, the research focus began to turn to biodegradable materials (Qiao Haijun, 2007), which can be classified as microorganism synthetic polymer, chemical synthetic polymer and natural polymer.

Currently, the research of biodegradable film mainly focuses on the following aspects: (1) photo-degradation film, it is made of resin mixed with photo-sensitizer and accelerator. (2)

Study on Manufacturing Technology and Performance of Biogas Residue Film 271

Wei to study the biodegradability (2009), observation method only can describe the film degradation process and the weight reduction method can quantitatively explain the

In this chapter, the physical properties and chemical composition of the biogas residue produced by anaerobic fermentation using ruminant feces were determined and analyzed; manufacturing technology and performance of biogas residue film was studied by the methods of central composite quadratic rotatable orthogonal experiment; biogas residue fibre mulching for planting eggplant was studied with the method of random plot

**2. The physical components of biogas residue and the chemical components** 

Composition Quality/ g Percentages/% Fibre 477 64

Table 2-1 showed that biogas residue was composed of three parts, fibre proportion was maximum, mineral proportion was minimum. There were mainly plastic, hair and grass

The determination of each component fibre and mineral content was shown in table 2-2.

Table 2-2. The fibre and minerals content and their mass percentages of each group

1 mm was maximum, minerals quality percentage of more than 5 mm was min.

Table 2-2 showed that fibre quality percentage of 0.25 mm to 0.5 mm was maximum; fibre quality percentage of more than 0.5 mm was min; minerals quality percentage of 0.5 to

Group /mm 0.25~0.5 0.5~1 1~2 2~5 >5 total Fibre quality /g 158 124 59 126 10 477 Minerals quality /g 0.8 5 1.3 0.7 0.2 8 Fibre quality percentages /% 21.10 16.50 7.90 16.80 1.40 64 Minerals quality percentages /% 0.11 0.67 0.17 0.09 0.03 1

The determination of physical components of biogas residue was shown in table2-1.

Non-mineral impurity 265 35 Mineral 8 1

Table 2-1. Biogas residue physical composition and their mass percentages

**2.1.1 Each component fibre and mineral content of biogas residue** 

degradation process of biodegradable film.

**2.1 The physical components of biogas residue** 

experiment.

**of biogas residue fibre** 

seeds in the non-mineral impurities

**2.1.2 Fibre morphology** 

Fig. 2-1 showed the fibre morphology of each group.

biodegradable film, it includes structural degradation film, biodegradable film containing inorganic salts and adding starch. (3) photo- biodegradable film; (4) plant fibre film.

In China, the major research was additive photo-degradation film and synthetic photodegradation film. The research focused on using light stabilizers to control degradation period. Since 1997, 944-polymeric efficient light stabilizer, BW-6911 new light stabilizer were developed, which replaced the severe irritation and sensitization GW-504/2002 anti-aging system. American Dupont CO. , Ltd produced copolymers of ethylene and CO, American OCC and DOW CO. , Ltd had used this technology to produce film and develop industrial production (Xiong Hanguo, 2004). The disadvantages of photo-degradation film were susceptible to external environment, which was difficult to control the degradation period , and covering field, the part into soil can not be degraded, so its application was limited (Xu Xiangchun, 2006).

The degradation of biodegradable film was caused by microbes in natural environmental condition. It was divided into additive biodegradable film and completely biodegradable film according to degradation mechanism and damage style.

At present, additive biodegradable film was composed of plastic, starch, compatibility agents, self-oxidants, processing additives. Typical varieties were polyethylene starch biodegradable film (Liu Ming et al., 2008). There were institutes of physics and chemistry, Beijing University of Technology, Guangdong biodegradable plastic CO., Ltd more than 20 research institutes. The research focused adding starch or modified starch into PE.

The main varieties of completely biodegradable film were PLA, PCL, and PHB and so on. United States used PCL to produce synthetic polymer biodegradable film (KAM Abd I Jkader, 2002). Warner-Lambert developed a new type of resin, which was made of 70% amylopectin starch and 30% amylose starch (He Aijun, 2002). It had good biodegradability, was considered a significant development in material science.

Photo-degradation film was made of additive photo-sensitizer, auto-oxidants, and antioxidants as microbial culture medium in general polymer.

Plant fibre film has good ventilation, wet and dry strength and good biodegradability. Chinese academy of agricultural sciences successfully developed the environmentallyfriendly hemp film (Fu Dengqiang, 2008). In addition, paper films composed of different materials were produced. South China Technology University used sugar cane and starch as materials to manufacture a kind of fully degradable film (Tan Chengrong, 2002). Japan manufactured biodegradable film with 1%-10% chitosan cloth softwood mechanical pulp original paper in 1990. The demand of environmental film increased in Washington State University, France, Germany, Italy, Canada, Netherlands and South Korea and other countries, leading to the environmentally-friendly film industry rapid development (Han Yongjun, 2008).
